Python FizzBuzz with lookup sets

fizzbuzz_sets.py

import cProfile
import pstats
import StringIO

pr = cProfile.Profile()
pr.enable()

threes = {num for num in range(3, 100, 3)}
fives = {num for num in range(5, 100, 5)}
not_in = {num for num in range(1, 100) if num not in threes and num not in fives}
both = threes.intersection(fives)

iNot = set()
iFizz = set()
iBuzz = set()
iFizzBuzz = set()
span = range(1, 101)


def calc():
    for num in span:
        if num in not_in:
            iNot.add(num)
        elif num in both:
            iFizzBuzz.add(num)
        elif num in threes:
            iFizz.add(num)
        else:
            iBuzz.add(num)

for i in xrange(0, 1000000):
    iNot.clear()
    iFizz.clear()
    iBuzz.clear()
    iFizzBuzz.clear()

    calc()
pr.disable()

print "3's: {}".format(len(iFizz))
print "5's: {}".format(len(iBuzz))
print "both: {}".format(len(iFizzBuzz))
print "neither: {}".format(len(iNot))

s = StringIO.StringIO()
sortby = 'cumulative'
ps = pstats.Stats(pr, stream=s).sort_stats(sortby)
ps.print_stats()
print s.getvalue()